Primer tube for dynamite cartridges



June 6, 1944, ca. R. MUSTAPARTA PRIMER TUBE FOR DYNAMITE CARTRIDGE Filed March 25, 1941 Fla- * FIG.-3

GEORGE R MUSTAPARTA INVENTOR.

Y W @9- g- Patented June 6, 1944 PRIMER TUBE FOR DYNAM'iTE CARTRIDGES George R. Mustaparta, Kingston, N. Y., assignor to Hercules Powder Company, Wilmington, Del., a corporation of Delaware Application March 25, 1941, Serial No. 385,087

7 r 6 Claims.

This invention relates to explosive primer de- There are many ways of making a primer.

Thus according'to one method the cap is inserted into a hole made in the end of the car.- tridge and the cartridge paper folded around the cap and tied. According to another method the cap is inserted through the side of the cartridge and the fuse tied to or looped around the cartridge. Other modifications of the above methods arepossible; However, in all of them the firing device is attached to or inserted in the completed dynamite cartridge in some manner.

In many operations, the primers described above are made up at a point remote from the shooting face to provide an added degree of safety and toeffect a saving in loading and firing time. In other operations, due to company rules, local law, etc., it is necessary to take the l explosive cartridges and caps to the shooting face separately and there prepare the primers. This type of operation is time consuming and adds a, considerable element of danger, particularly under conditions where the operator is working in semi-darkness. Even whenthe primers are prepared beforehand the prior art methods are subject to the disadvantage ofbeing tedious and time consuming.

v In orderto overcome these difficulties it has beensug ested that a complete unit comprising a tubular member of cardboard, paper or other suitable material be made up and that the firing device made an integral part 'of this unit. Such a device has been called a primer tube, andis described and claimed in the copen'ding application of Lawrence W. Early, Serial No. 299,161, filed October 12, 1939, now PatentNd. 2,301,334-.' Thus, when it is desired to make the primer it is only necessary to insert the'ex'plosive cartridgeinto the tubular them-- her or'primer tube. This can be done very e'asily and'expeditiously by the operator eve under conditions of semi-darkness.

zinThe present invention relates to improvements in primer tubes whereby the insertion of an explosive cartridge is rendered easier and less likely to loosen or dislodge the firing device.

It .is, therefore, an object of the present inventlon to construct a primer tube device which permits the easy and quick asembly of a complete primer, even under very adverse conditions.

It is a further object of the invention to provide a primer tube, having a blasting cap securely fastened thereto in such manner that an explosive cartridge may be quickly and easily inserted into the tube in priming relation with the cap, and without dislodging the cap.

It is a still further object of the invention to provide a tubular member having a blasting cap securely attached thereto such that an inserted explosive cartridge will be firmly and securely held in priming relation with the detonating end of the blasting cap.

A further object of the invention is the provision of a primer tube in which the attached blasting cap is covered partially or completely by a ramp member thus facilitating insertion of a dynamite cartridge.

A still further object of the invention is the provision of a primer tube having an electric blasting cap securely attached thereto and which serves, when an explosive cartridge is not insert'ed, as a container for the leg wires of the electric blasting cap.

Another object of the invention is the provision of a primer tube which overcomes the disadvantages of prior known methods of priming explosive charges.

Other objects will appear hereinafter.

The objects of my invention are, in general, accomplished by providing a tubular member, herein designated a primer tube, which is of such diameter and length that an explosive cartridge may be easily but snugly inserted therein. The tubular member may desirably consist of an outer, comparatively rigid, member and an inner member which snugly fits inside the outer member. A blasting cap is threaded through slits in the tubular member and has its inner portion securely held in place between the inner and outer members. The inner end of the cap is entirely covered by the inner member, thus forming a ramp which'allows the dynamite cartridge, even though quite hard, to slip over the end of the cap. The inserted cartridge is in close priming relation with the blasting cap and may be readily detonated thereby.

Having now indicated in a general way the nature and purpose of the present invention, there follows a more detailed description of a preferred embodiment thereof, with reference to the accompanying drawing, wherein Figure 1 is a longitudinal view of the device; Figure 2 is a cross-sectional view on line 2--2 of Figure 3; Figure 3 is a longitudinal cross sectional view taken on line 33 in Figure 1; Figure 4 is a longitudinal view showing the primer tube with an inserted explosive cartridge and Figure 5 is a .-,cross-sectional.view taken on line -5 of Figprefer to make each of these members of double layer construction, the outer member 2 of two layers of cardboard glued together and the inner layer 3 of two layers of heavy paper glued together.

' In joining the blasting cap to the tubular members in accordance with the present invention a transverse slit 6 is made through all four layers of material as shown more particularly in Figures l and 3. A second transverse slit I is then made in the two outer layers of cardboard only. The section of the tube between the two slits is then pushed inwardly to form a loop 8 (Fig. 2) and the blasting cap inserted through the loop and-inwardly between the outer tubular member 1 2 and'the inner tubular-"member 3. The resulting construction is clearly shown in Figures 2 and 3. It will be noted that the outer portion of the blasting ca'p rests at its upper portion against the under side of the inner and outer tubes; the intermediate portion of the cap rests at its lower portion in theloop 8 which is formed by the inner tubular-member 3 and the portion tubular member .1. Alternatively, this open space may be filled with a material such as, for example, glue, rosin, plastic or molten sulfur.

Uponhardening, this material will adequately support the :portion it; of the ramp i2 and will,

in addition, aid in positively positioning the blasting cap. i

fI'he ramp l2 allows a dynamite cartridge, even I though quite hard, to slip easily over the end of the cap. At the same time the split tube construction, together with the paper covering, serves to keep the capfrom becoming dislodged. With 'the primer tube mentioned heretofore, when the end of the blasting cap is left exposed it is sometimes'necessary, particularly in the case of hard dynamite, to have a groove pressed in the dynamite to permit easy insertion and lessen the likelihood of the blasting cap being loosened when the cartridge is inserted.

Another feature of the invention is that the primer tube, when not in use to prime a dynamite .cartridge as, for example, during shipping thereof, may serveas a container in which the leg wires 9 and ID of the attached electric blastof the outer tubular member 2 between the slits 6 and 1;. the inner portion'of the cap'rests in the recess 4 formed by the inner tubularmember 3 and the outer tubular member 2. .This construction forms a very snug pocket for the blasting cap permitting it to be held firmly in place and preventing accidental displacement by the insertion of the dynamite cartridge. If desired,'a material such as, for example, glue, rosin, plastic or molten sulfur may-be poured into the tubular recess and allowed to harden in order to more positively position the blasting cap.

One of the important features of the improved primertube according to the present invention is the provision of a ramp 12 over the blasting cap, particularly over the inner portion thereof.

ing cap may be securely and expeditiously pack aged. For this purpose, the leg wires of the cap are folded in the conventional accordion fold'and the bundle inserted in the primer tube- I. The leg wires 9 and it may, if desired, be'tagged to indicate the delay period of the delay electric blasting cap used in the device or the delay period may be printed on the outsideof the primer tube itself.

'Figures=4-and-5 indicate how the primer tube I of this invention isto be combined with a dynamite cartridge ll to'quickly effect the 'construction of a primer ready for use in any explosive operation. Thus theleg wires are removed from 1 the primer tube and'the' dynamite cartridge ii inserted as shown. The size of the tube l and of the dynamite cartridge-ii are coordinated so that the cartridge is easily slipped into the tube but in such a manner-that a snug fit is main- In the construction shown, the ramp I2 is formed.

by a depressed portion of the inner tubular memher 3 and extends from a position under the loop 8 back to a position somewhat beyond the end of the blasting cap. It will be noted that the ramp has a gradual slope from its maximum obstruct-,

ing position to and'into the periphery of the inner tube 3. The ramp i2 is supported for the greater part of its length by the enclosed portion of the blasting cap against which it bears.

desirable to provide additional supporting means for the portion 1 3. This may be accomplished in any suitable manner as by the insertion of a solid material having the shape of the open space tained and close contact is produced between the dynamite cartridge and the detonating end of the blasting cap.

It will be realized that various modifications of the device may be resorted to without departing from the spirit and scope of the invention. Thus, for example, in some cases it may be desirable to use a paper sticker in addition'to. or in place of the innertubular member..- Such a sticker may be made to cover the detonating end of the blasting cap and thus hold it securely in position while at the same time forming a ramp which would facilitate insertion of the dynamite cartridge. This type of construction is very simple and can be used either with or without the loop means 8. If desired, the primer tube of the present invention may be provided with an env the blasting cap. Also, if desired, the inner tubular member may be glued or otherwise fastened to the-outer tubular member. In some cases the primer tube may be split longitudinally to permit its.use with various 1 sizes of cartridges. In such an event the tube should inherently have or be provided with means to produce sufllcient resiliency to securely grip the cartridge. In some cases it may be desirable to provide a plurality of loops 8 rather than the one shown although defined between the portion l3 and the outer 1 I have found that the-one loop gives very satisfactory results.

Although I have used electric blasting caps as illustrative it is to be understood that other types of commercial electric firing devices such as delay electric blasting caps, fuse blasting caps, etc., may sometimes be used.

It is desirable after the assembly of the complete primer tube to dip the tubes into molten parafiin, rosin-parafiln and/or mixtures of similar materials. This aids in holding the entire assembly together and inwater proofing the device.

The primer tube of this invention is particu- ...larly useful where it is necessary to prepare primers quickly and under -adverse conditions such as, for example, at a tunnel face. It cansumes less time and is less dangerousthan the old method of making a hole in the dynamite cartridge, inserting a blasting captherein, and

taking the necessary precaution to prevent the cap from being pulled out of the cartridge during the bore hold loading operations. It is much simpler and easier than prior methods thus requiring less skill and labor on the part of the operator. It has the further advantage that a dynamite cartridge may be quickly and easily inserted without loosening or disiodging the firing the tubular member for mounting the firing device adjacent the peripheral portion of the tubular member in a snug non-slipping relationship, a lining member within said tubular member which is at least partially cylindrical and which forms a ramp over the'said detonating end of the firing device whereby an inserted explosive cartridge siips easily over the said detonating end of the firing device and is held in priming contact therewith.

2. A priming device adapted to receive and prime an explosive cartridge comprising an elongated shock-resistant substantially tubular member, an electric firing device provided with lead wires and having a detonating end, resilient means associated with the tubular member for mounting the firingdevice adjacent the circumferential portion of said tubular member in a snug non-slipping relationship, said mounting means being constructed and arranged to hold the firing device in a position suchthat the detonating end thereof is disposed within the interior of the tubular member, a lining member within said tubular member which is at least partially cylindrical and which forms a ramp over the detonating end of said electric firing device whereby upon insertion of an explosive cartridge into the primer the detonating end of the firing device will not form an obstruction and whereby said inserted explosive cartridge has priming contact with said detonating end, said primer serving as a packing case for the lead wires prior to the insertion of an explosive cartridge therein.

3. A priming device adapted to receive and prime an explosive cartridge comprising an outer paper tube, an inner paper tube snugly fitted within the outer paper tube, said inner paper tube being provided with aninwardly extending portion forming a tubular recess, said recess extending longitudinally of the inner tube, a firing device positioned in said recess and securely fastened therein, a ramp formed by said inner tube from the detonating end of said firing device to the inner periphery of said outer tube and said inner tube having a resistance whereby when an explosive cartridge is inserted into thesaid priming device, the detonating end of the said firing device will be in priming contact with the said cartridge.

4. A priming device adapted to receive and prime an explosive cartridge comprising a shockresistant tubular member, said member having a series of transverse cuts dividing'a longitudinally extending portion of the surface of said member into a plurality of relatively movable sections, an electric firing device threaded -through said sections so that one section passes above the firing device and the adJacent section below it, said "firing device having a detonating end extending into the tubular member, a lining member within said tubular member which is at least partially cylindrical and which forms a ramp from the end of said device to the inner surface of said tubular member whereby an explosive cartridge is easily inserted into the said priming device and the detonating end of the said firing device will be in'priming contact with the said cartridge.

5. A priming device adapted to receive an explosive cartridge to effectively prime the same comprising a preformed substantially tubular shock-resistant member, a firing device, resilient means for rigidly attaching said firing device to and adjacent the wall of said shock-resistant member in a snug non-slipping relationship, said firing device positioned such that the detonating end thereof is disposed within the tubular member, a lining member within said tubular member which is at least partially cylindrical and which forms a ramp extending from the detonating end of said firing device to the inner surface of said shock-resistant member whereby an explosive cartridge will be easily inserted and will be in priming contact with the detonating end of the said firing device.

6. A priming device adapted to receive and prime an explosive cartridge comprising a longitudinal split tubular member, a series of transverse peripheral cuts in said member adiacent one end thereof, said cuts dividing a longitudinally extending portion of the surface of the tubular member into a plurality of relatively movable strips, an electric firing device threaded through said strips in a manner such that one series of alternate strips pass under the firing device and another series of alternate strips pass over the firing device, said firing device having a detonating end projecting into the tubular member, a lining member within said tubular member which is at least partially cylindrical and which forms a ramp extending from said detonating end of said firing device to the inner surface of said tubular member and a label wrapped around said tubular member and firing device and aiding in holding them in assembled position.

GEORGE E. MUSTAPARTA. 

